Invalid redefinition error for const X = Vector{<:A}

Internals & Design
1

When the following lines are run twice, the error invalid redefinition of constant X is thrown. The code is rather random, but it is the most minimal example I could come up with without removing the problem. In particular, foo does neither use A nor X but is essential.

abstract type A end
struct B <: A
    r
end
const X = Vector{<:A}
function foo(b::B)
    r = b.r
    i = 1
    for j in 1:length(r)
        while r[j] > 0 && i<10
             i+=1
        end
    end
end

Using the line X = Vector{T} where {T<:A} works fine instead, even though Vector{<:A} == Vector{T} where {T<:A} returns true.

Does anyone know what might be going on? This initially caused me to use @isdefined each time, but this seems unintended.

2

I can reproduce on 1.7 but not 1.8 — this very well may have been a bug.

2 Likes
3

Sounds good. Thank you for quickly testing it.

1 Like